CN101288240B - Method and apparatus for transmitting and receiving data in a CDMA system - Google Patents

Abstract

A method and apparatus are provided for transmitting data from an access node to an access terminal in a Code Division Multiple Access (CDMA) system operating at least 128 Media Access Control Identifiers (MAC IDs) in a sector. The method involves configuring a preamble group for transmitting Multi-User Packets (MUPs) to a specific access terminal, providing the terminal with information about the preamble group, and transmitting data to an access terminal with a MAC ID of 128 or higher using a preamble corresponding to the MAC ID. If the specific access terminal has a MAC ID of 128 or higher, the preamble group includes at least one preamble, which the access terminal uses to determine whether it has received the MUP. The access node provides the access terminal with information about the preamble group during session configuration.

Description

Method and apparatus for transmitting and receiving data in code division multiple access system

technical field

The present invention generally relates to methods and systems for transmitting and receiving data in a mobile communication system. More particularly, the present invention relates to a method and apparatus for transmitting and receiving data to/from a plurality of users in a Code Division Multiple Access (CDMA) system using Multi-Carrier (MC).

Background technique

Recently, a great deal of research on high-speed data transmission in a CDMA mobile communication system is being conducted. A typical mobile communication system having a channel structure for high-speed data transmission includes a 1x Evolution Data Only (1xEVDO) system. The 1xEVDO system is a mobile communication system specified in the 3rd Generation Partnership Project 2 (3GPP2), which is used to supplement the data communication of the Interim Standard-2000 (IS-2000) system.

The forward channels of the 1xEVDO system include a pilot channel, a forward medium access control (MAC) channel, a forward traffic channel, and a forward control channel. The forward channel is sent to each access terminal (AT) by time division multiplexing (TDM). A bundle of signals sent via TDM is called a 'burst'.

The forward traffic channel transmits user data packets, while the forward control channel transmits control messages and user data packets. The forward MAC channel is used for reverse rate control, delivery of power control information, and assignment of forward data transmission channels.

Different from the forward channel, the reverse channel of the 1xEVDO system has a channel with an identification code unique to each individual access terminal, and the reverse channel of each individual access terminal includes a pilot channel, reverse traffic channel, access channel, data rate control (DRC) channel, and reverse rate indicator (RRI) channel. The reverse traffic channel sends user data packets, the DRC channel is used to indicate the forward rate that the access terminal can support, and the RRI channel is used to indicate the data channel transmission rate in the reverse direction. Access channels are used when an access terminal sends messages or traffic to an access node (AN) prior to the traffic channel connection.

The architecture of the 1xEVDO system will now be described with reference to FIG. 1 .

FIG. 1 is a diagram schematically showing the architecture of a conventional 1xEVDO system.

Referring to Fig. 1, this 1xEVDO system comprises: packet data service node (PDSN) 40, is connected to Internet network 50, is used for sending high-speed packet data to access node 20; And access node controller (ANC) 30, is used for controlling Access node 20. Access node 20 communicates wirelessly with a plurality of access terminals (AT) 10, and transmits the high-speed packet data to access terminal 10a having the highest rate.

For rate control of the forward channel, the access terminal 10 measures the received strength of the pilot signal transmitted by the access node 20 and determines its desired forward data rate based on the measured received strength of the pilot signal. The access terminal 10 sends DRC information corresponding to the determined forward data rate to the access node 20 over the DRC channel. The access node 20 then receives the DRC information and may only send packet data to access terminals 10a with good channel conditions at the rate reported by the access terminals 10a. While the mapping between forward channel state and DRC information varies depending on implementation, it is typically fixed during access terminal manufacturing.

Table 1 shows the relationship between DRCs reported by access terminals and their associated rates and transport formats.

Table 1

DRC Rate(kbps) Number of transmissions (number of slots) transmission format 0x0 0 16 (1024, 16, 1024) 0x1 38.4 16 (1024, 16, 1024) 0x2 76.8 8 (1024, 8, 512) 0x3 153.6 4 (1024, 4, 256) 0x4 307.2 2 (1024, 2, 128) 0x5 307.2 4 (2048, 4, 128) 0x6 614.4 1 (1024, 1, 64) 0x7 614.4 2 (2048, 2, 64) 0x8 921.6 2 (3072, 2, 64) 0x9 1228.8 1 (2048, 1, 64) 0xa 1228.8 2 (4096, 2, 64) 0xb 1843.2 1 (3072, 1, 64) 0xc 2457.6 1 (4096, 1, 64) 0xd 1536 2 (5120, 2, 64) 0xe 3072 1 (5120, 1, 64)

Referring to Table 1, the transmission format is expressed in the form of bits, slots, and chip preambles, for example, (1024, 16, 1024), which means that 1024-bit information is sent with 16 slots and sent before the transmission starts 1024-chip preamble. The access node sends data to each access terminal in the transport format corresponding to the DRC value reported by the access terminal, while the access terminal attempts to receive the forward data channel only in the format corresponding to its reported DRC value. This agreement is reached because, for the data channel sent in the forward direction, there is no other channel for indicating its data rate. That is, when the access node sends data using a transport format other than that reported by the access terminal, the transport format cannot be indicated, so the access terminal cannot receive the data. Thus, the access node always only sends data in the transport format corresponding to the DRC reported by the access terminal. For example, for an access terminal sending DRC0x01 over a DRC channel, the access node sends data using the transport format (1024, 16, 1024) corresponding to that DRC value, and the access terminal attempts to receive data in that format only.

The access node, when sending data to the access terminal, uses a preamble of a length specified in the transport format to indicate which user should receive the forward data. The preamble is generated by extending a predefined bit sequence with a Walsh code corresponding to a Medium Access Control Identifier (MAC ID) assigned to each access terminal by the access node. To determine whether to receive data, an access terminal receives as many chips as the preamble length corresponding to its reported transport format, despreads the received chips using the Walsh code corresponding to its own MAC ID, and The strength and value are compared to see if the signal is equal to the predefined bit sequence.

The packet data sent by the access node to an access terminal based on the received DRC information is called a "Single User Packet (SUP)". For general data services, the access node uses the SUP to send data. Compared with general data services, Voice over Internet Protocol (VoIP)-based data services require a lower transmission bandwidth of about 9.6 kbps. For a bandwidth of 9.6kbps, only about 192 bits of data are sent every 20ms. Sending such a small amount of data with a minimum SUP size of 1024 bits results in unnecessary waste of bandwidth. In order to avoid such waste of resources in the radio access section, a scheme has been proposed to transmit data of several users using one physical packet. Such a packet format is called "Multi-User Packet (MUP)".

Table 2 shows the relationship between the DRC value and its associated rate and the transmission format of the MUP.

Table 2

DRC Rate(kbps) List of associated multi-user transfer formats 0x0 0 (128, 4, 256), (256, 4, 256), (5 12, 4, 256), (1024, 4, 256) 0x1 38.4 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256)

0x2 76.8 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256) 0x3 153.6 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256) 0x4 307.2 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256) 0x5 307.2 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128) 0x6 614.4 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256) 0x7 614.4 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128) 0x8 921.6 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64) 0x9 1228.8 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128) 0xa 1228.8 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64), (4096 , 2, 64) 0xb 1843.2 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64) 0xc 2457.6 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64), (4096 , 2, 64) 0xd 1536 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64), (4096 , 2, 64), (5120, 2, 64) 0xe 3072 (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4, 128), (3072, 2, 64), (4096 , 2, 64), (5120, 2, 64)

For each individual DRC reported by an access terminal, the IxEVDO system defines a multi-user group compatible with that DRC as shown in Table 2. For example, an access terminal sending DRC 0x5 should receive the same transport formats as (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256), (2048, 4 , 128) the corresponding multi-user grouping. The multi-user packet includes packet data for several users and is sent along with the addresses of the access terminals that will receive each data packet. Upon receipt of a multi-user packet, the access terminal determines whether its own MAC ID is included in the received packet, and processes the corresponding user packet only if its own MAC ID is included in the received packet.

FIG. 2 is a diagram showing the structure of a multi-user packet used in a conventional 1xEVDO system. With reference to Fig. 2, the composition of multi-user grouping 200 is: header 210, indicates the MAC ID of receiver's access terminal, or the address and the length of the data that sends to this access terminal; Boundaries with Others; Payload 230, including data; Filler 240; and Trailer 250.

The header 210 of the multi-user packet conveys the information necessary for each access terminal receiving the multi-user packet to receive the multi-user packet. The information is composed of: format field 211, which includes format information of the transmission data; MAC ID 213, which is the identifier of the receiving terminal's access terminal; and length field 215, which indicates the length of the transmission data. Here, the transmission data refers to the transmission data in the multi-user group 200, and will be referred to as a user group.

A header 210, comprising N received information elements pertaining to N recipient access terminals, followed by a delimiter 220 '00000000' for defining the boundary between the header part and the payload part. The delimiter 220 is followed by a payload 230 comprising user packets for N access terminals according to the data format and length, and order, specified in the previously transmitted/received information. If necessary, a filler 240 may be added behind the payload 230 , and finally a tail 250 fixed as '00' is placed after the filler 240 to generate a multi-user packet 200 .

The multi-user packet 200 is transmitted using the preamble allocated for transmitting the multi-user packet. Five types of preambles for multi-user packets are defined according to the rate of multi-user packets. For example, one preamble (preamble number 66) can be used for low-rate multi-user packets (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4 , 256), one preamble (No. 67 preamble) can be used for multi-user packets (2048, 4, 128), and different preambles (No. 68, No. 69, and No. 70 preamble) Can be used for multi-user groups (3072, 2, 64), (4096, 2, 64), (5120, 2, 64) respectively. After reporting the DRC, the access terminal monitors for the arrival of a preamble corresponding to a multi-user packet compatible with the transmitted DRC. After receiving the preamble corresponding to a multi-user packet compatible with its own DRC, the access terminal decodes the multi-user packet, determines whether its own address is contained in the header portion, and if the header portion contains its own The address then reads from the payload section and processes the user packet corresponding to the length specified in the header.

As the demand for higher data rates increases in mobile communication systems, multi-carrier EVDO systems have been proposed to achieve higher rates in 1xEVDO systems. Compared with traditional EVDO systems that use a single carrier to exchange data, multi-carrier EVDO systems allocate multiple carriers to an access terminal, thereby achieving higher rates. Because each carrier is capable of providing the maximum rate provided by a conventional IxEVDO system, an access terminal communicating using multiple carriers can use the maximum data rate in an ideal environment as a function of the number of carriers.

In such a multi-carrier system, because an access terminal receives more than one carrier, the number of access terminals receiving data for each individual carrier increases on average. Thus, there is a need for a method that can provide as many MAC IDs per individual carrier as the number of access terminals increases. In addition, for the sake of simple switching, the multi-carrier system should not make too many changes to the physical transmission structure of the existing 1xEVDO system in the existing nationwide network.

Contents of the invention

Accordingly, it is an object of exemplary embodiments of the present invention to provide a method for more efficiently transmitting and receiving data to and from multiple access terminals in a code division multiple access (CDMA) system using multiple carriers (MC). methods and devices.

Another object of exemplary embodiments of the present invention is to provide a data transmission/reception method and apparatus capable of reducing overhead in a CDMA system using MC.

Exemplary embodiments of the present invention provide a method for transmitting data by an access node to an access terminal in a Code Division Multiple Access (CDMA) system. The method includes: configuring information about a preamble used to transmit a multi-user packet (MUP) to an access terminal; providing the access terminal with information about the preamble; and using a preamble corresponding to the access terminal A synchronization code sends the MUP to the access terminal.

In an exemplary implementation, the information on the preamble includes at least one preamble.

In an exemplary implementation, the access node provides information regarding the preamble to the access terminal during session configuration.

In an exemplary implementation, transmitting the MUP includes: examining data rate control (DRC) information received from an access terminal; and transmitting the MUP using a preamble assigned to the access terminal.

In an exemplary implementation, transmitting the MUP includes transmitting the MUP using a preamble determined from information about the preamble and a size of the MUP to the access terminal.

Exemplary embodiments of the present invention provide an access node in a Code Division Multiple Access (CDMA) system. The access node includes a controller configured to configure information about a preamble used to transmit a multi-user packet (MUP) to an access terminal and to check data rate control (DRC) information received from the access terminal; a radio frequency (RF) unit for sending information to the access terminal about a preamble for a multi-user packet (MUP), and sending the access terminal information to the access terminal using the preamble assigned to the access terminal based on the DRC The terminal sends the MUP.

In an exemplary implementation, the information on the preamble includes at least one preamble.

In an exemplary implementation, the controller transmits the MUP to the access terminal using a preamble determined from information about the preamble and a size of the MUP.

A further exemplary embodiment of the present invention provides a method for receiving data by an access terminal in a Code Division Multiple Access (CDMA) system. The method comprises: receiving from an access node information about a preamble for a multi-user packet (MUP); detecting whether there is a preamble assigned to the access terminal itself after receiving data from said access node code; and decoding the MUP when there is a preamble assigned to the access terminal itself.

In an exemplary implementation, the method further includes determining a preamble based on information about the preamble and a size of the MUP to the access terminal.

In an exemplary implementation, the information on the preamble includes at least one preamble.

In an exemplary implementation, the access terminal receives information regarding the preamble during session configuration with the access node.

In an exemplary implementation, the step of receiving an assigned MUP includes: checking a preamble assigned to the access terminal itself when the access terminal is assigned a MAC ID number 128 or higher; The access terminal decodes the MUP from its own preamble.

A further exemplary embodiment of the present invention provides an access terminal in a Code Division Multiple Access (CDMA) system. The access terminal includes a radio frequency (RF) unit configured to transmit data rate control (DRC) information to an access node and to receive information from the access node about packets allocated to the access terminal itself for multi-user packets ( information of the preamble of the MUP); a controller for controlling the DRC to be sent to the access node; and a decoder for when the data allocated to the access node is received after receiving the data from the access node The MUP is decoded when accessing the terminal's own preamble.

In an exemplary embodiment, the controller determines the preamble further based on information about the preamble and a size of the MUP to the access terminal.

In an exemplary embodiment, the information on the preamble includes at least one preamble.

In an exemplary embodiment, the controller receives information about the preamble during session configuration with the access node.

In an exemplary embodiment, when the access terminal is assigned a MAC ID number 128 or higher, the controller checks the preamble assigned to the access terminal itself, and when there is a preamble assigned to the access terminal The MUP is decoded when entering the terminal's own preamble.

In an exemplary embodiment, the controller further checks a preamble of a commonly allocated MUP.

A further exemplary embodiment of the present invention provides a method for transmitting data by an access node to an access terminal in a Code Division Multiple Access (CDMA) system. The method includes: receiving data rate control (DRC) information from an access terminal; scheduling, based on information about a set of preambles for a MUP, a method for utilizing a multi-user packet (MUP) among access terminals assigned the same preamble. ) an access terminal that sends data, and sends the received DRC and MUP; and configures the MUP, and uses the preamble to send the configured MUP.

Description of drawings

The above and other objects, exemplary features, and advantages of the present invention will become more apparent from the following detailed description of certain exemplary embodiments thereof in conjunction with the accompanying drawings, wherein:

FIG. 1 is a diagram schematically showing the architecture of a general 1xEVDO system;

FIG. 2 is a diagram showing the structure of a multi-user group used in the 1xEVDO system;

3 is a diagram illustrating a format structure of a multi-user packet according to an exemplary embodiment of the present invention;

4 is a flow diagram illustrating preamble detection operations in an access terminal according to an exemplary embodiment of the present invention;

5 is a flowchart showing a data transmission method in an access node according to an exemplary embodiment of the present invention; and

6 is a block diagram of an access node and an access terminal, according to an exemplary embodiment of the invention.

Throughout the drawings, like reference numerals should be understood to refer to like elements, features, and structures.

detailed description

The contents illustrated in this specification are provided to help comprehensive understanding of various exemplary embodiments of the present invention disclosed with reference to the accompanying drawings. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the exemplary embodiments described herein can be made without departing from the scope and spirit of the claimed invention. Descriptions of well-known functions and constructions are omitted for clarity and conciseness.

Exemplary embodiments of the present invention provide methods and apparatus for efficiently transmitting an increased number of user packets per individual carrier, using Multi-User Packetization (MUP), without impacting existing access terminals in a multi-carrier system , and do not change too much the physical transmission structure of the existing EVDO system that has already formed a nationwide network.

To this end, an exemplary embodiment of the present invention provides a method for defining a plurality of multi-user packet reception groups and corresponding preamble groups, and assigning a specific multi-user packet reception group to each user. Afterwards, exemplary embodiments of the present invention will present a method for transmitting data to an access terminal using a preamble group allocated by an access node and a multi-user packet structure.

First, the multi-user grouping used in the exemplary embodiment of the present invention will be described. To support an increased number of multi-carrier access terminals while maintaining the architecture of legacy systems, the exemplary embodiment of the present invention defines 256 new access terminal identifiers (7-bit MAC IDs) in addition to the traditionally used 128. The access terminal identifier (8-bit MAC ID). Thus, in the method proposed by the exemplary embodiments of the present invention, the maximum number of access terminals that can be supported by one sector is 384.

Since it is assumed here that the architecture of the legacy system is maintained, it is not possible to additionally allocate new physical layer preambles to the newly defined 256 access terminal identifiers in addition to the conventionally defined 128 access terminal identifiers. Thus, the old Single User Packet (SUP) cannot be used in situations where preambles numbered 0 to 127 are utilized to distinguish recipient access terminals. Exemplary embodiments of the present invention present a MUP structure for transmitting data to access terminals corresponding to the newly defined 256 access terminal identifiers. Since a traditional multi-user packet is demodulated and decoded by multiple access terminals, when it is sent, the identifier of its actual receiver is written in the header to indicate the actual receiver. An exemplary embodiment of the present invention presents a new multi-user packet header for designating newly defined 256 identifiers.

FIG. 3 is a diagram showing the format structure of a multi-user packet 300 according to an exemplary embodiment of the present invention, and includes old access terminal identifiers and newly added access terminal identifiers. As shown in FIG. 3, a header 310 for the newly defined 256 access terminal identifiers MAC ID 128 to 384 exists at the end of the multi-user packet 300 and includes information 311 indicating the access terminal (by inserting terminal's identifier minus 128), the length 313 of the corresponding access terminal's packet contained in the multi-user packet, and the header 310 used to distinguish it from the newly added access terminal's data portion 301 delimiter 303.

If the conventionally defined multi-user group and the preamble assigned to it (ie, preamble No. 66 to No. 70) are used to transmit data for the newly defined 256 identifiers MAC ID 128 to 384, then in each When an access terminal with an access terminal identifier number 128 or higher transmits data, all access terminals that have transmitted a DRC compatible with the multi-user packet format perform demodulation and decode the packet. For example, if an access terminal with identifier number 200 has reported a DRC compatible with multi-user group (1024, 4, 256), and the access node has used number 66 corresponding to multi-user group (1024, 4, 256) The preamble sends the multi-user packet (1024, 4, 256) to the access terminal, and all access terminals that have reported a DRC compatible with the multi-user packet (1024, 4, 256) receive the corresponding packet and respond to the The received packets are demodulated and decoded to determine that the received packets may have been addressed to themselves. That is, if many access terminals in a sector attempt to receive each time a packet is sent to an access terminal with an identifier number 128 or higher, the access terminal suffers from unnecessary wastage of energy. Thus, the present invention proposes a scheme for sending data to new multi-carrier access terminals without affecting legacy access terminals.

According to an exemplary embodiment of the present invention, to address the above problems, an access node assigns to an access terminal a set of preambles that the access terminal will use to receive multi-user packets. In an exemplary implementation, as a method for assigning a preamble group, the access node may deliver the preamble group with the access terminal identifier when assigning the access terminal identifier to the access terminal, or may use the new Defined messages to configure preamble groups. In a further exemplary embodiment, there is another method for assigning a preamble group as a session configuration attribute during session negotiation in which an access node negotiates information necessary for communication with an access terminal prior to transmission .

table 3

field length (bit) MessageID 8

{The following record appears NumForwardChannels times:

{The following records appear NumSectorsThisFrequency times:

TrafficMACIndex 8 MUP Preambles Included 1 MUPPreamble1 0 or 7 MUPPreamble2 0 or 7 MUP Preamble3 0 or 7 MUP Preamble4 0 or 7 MUP Preamble5 0 or 7

}

}

Table 3 shows a message for indicating a preamble group for receiving a multi-user packet proposed in an exemplary embodiment of the present invention. The preamble group defined in the exemplary embodiments of the present invention may be included in the TrafficChannelAssignment message sent when the access node assigns a traffic channel to the access terminal or updates the active set (activeset) of the access terminal, or may include It is included in the message newly defined for the preamble group.

A MessageID field of a message indicating a preamble group has a value of a message identifier for distinguishing a TrafficChannelAssignment message or a newly defined message from other messages. In addition, the message indicating the preamble group can deliver to the access terminal one access terminal identifier for each forward carrier in each sector that belongs to the access terminal's active set. The access terminal identifier is delivered using the TrafficMACIndex field.

The scheme proposed in the exemplary embodiments of the present invention can deliver a new preamble identifier (preamble group) for receiving multi-user packets in addition to the access terminal identifier. The MUPPreamblesIncludes field indicates whether a new preamble identifier proposed by an exemplary embodiment of the present invention is included. If the MUPPreamblesIncluded field is set to '1', the following MUPPreamble1, MUPPreamble2, MUPPreamble3, MUPPreamble4, and MUPPreamble5 fields are included in the message. The MUPPreamble1 field indicates a preamble for transmitting the multi-user packet (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256). The MUPPreamble2 field indicates the preamble used to transmit the multi-user packet (2048, 4, 128). The MUPPreamble3 field indicates the preamble used to transmit the multi-user packet (3072, 2, 64). The MUPPreamble4 field indicates the preamble used to transmit the multi-user packet (4096, 2, 64). The MUPPreamble5 field indicates a preamble used to transmit a multi-user packet (5120, 2, 64).

In the above embodiment, the access node sends a message including five MUPPreamble fields. However, if the access node sends the MUPPreamble1 field to the access terminal according to further embodiments, the access terminal may utilize the received MUPPreamble1 field to use MUPPreamble2 through MUPPreamble5 according to predetermined rules.

Table 4

Table 4 shows an exemplary method of delivering a preamble set proposed in an exemplary embodiment of the present invention for receiving a multi-user packet using configuration attributes negotiated between an access node and an access terminal during session negotiation.

An exemplary embodiment of the present invention defines additional configuration properties of MUPPreamble1, MUPPreamble2, MUPPreamble3, MUPPreamble4, and MUPPreamble5. The configuration attribute MUPPreamble1 indicates the preamble used to send the multi-user packet (128, 4, 256), (256, 4, 256), (512, 4, 256), (1024, 4, 256). The configuration attribute MUPPreamble2 indicates the preamble used to send the multi-user packet (2048, 4, 128). The configuration attribute MUPPreamble3 indicates the preamble used to send the multi-user packet (3072, 2, 64). The configuration attribute MUPPreamble4 indicates the preamble used to send the multi-user packet (4096, 2, 64). The configuration attribute MUPPreamble5 indicates the preamble used to send the multi-user packet (5120, 2, 64). If the value of each configuration attribute is '0x00', it means that the preamble group for receiving the multi-user packet proposed in the exemplary embodiment of the present invention is not used. Access terminals and access nodes may determine desired preamble identifiers among '0x05'-'0x3F' and '0x48'-'0x7F' as configuration attribute values.

In the above embodiments, the access node and the access terminal define five configuration attributes. However, if the access node and the access terminal define MUPPreamble1 according to another embodiment, then the access terminal can utilize MUPPreamble1 to use MUPPreamble2 through MUPPreamble5 according to predetermined rules.

If a particular access terminal receives a preamble group, that access terminal discards packets sent using preamble numbers 66 through 70 used to send legacy multi-user packets (MUPs). If instead a preamble belonging to a newly received preamble group is detected, the access terminal attempts to demodulate and decode the forward packet. Alternatively, after receiving the preamble group, the access terminal may attempt to receive both packets sent using preambles 66 to 70 used to send legacy multi-user packets, and packets sent using preambles belonging to the new allocation. The packet sent by the preamble of the sync code group.

An access node that has indicated a preamble set can use the indicated new preamble set to transmit the data of the corresponding access terminal in a multi-user packet instead of using numbers 66 to 70 for sending a conventional multi-user packet The data is sent with a preamble. As a further alternative, an access node that has indicated a preamble set may use either the preambles 66 to 70 used to send legacy multi-user packets, and the indicated new preamble set The data for the respective access terminals is transmitted using multi-user packets.

An access node may assign more than one preamble group considering its load conditions or the number of access terminals with identifier number 128 or higher. The access node may assign a preamble group to an access terminal with an identifier number 128 or lower, or an access terminal with an identifier number 128 or higher.

An access terminal assigned a preamble group monitors for the arrival of a multi-user packet format compatible with its reported forward rate information (DRC) and its corresponding preamble. As shown in Table 2, for a particular rate information (DRC), multiple multi-user packet formats may be mapped to it, and the access terminal should operate such that it detects all preambles corresponding to each of them.

Alternatively, to reduce the preamble detection load on the access terminal (i.e., reduce the number of preambles detected by the access terminal), the access terminal may monitor only those multi-user packet formats that are compatible with the transmitted rate information. Some of the multi-user packet formats with the highest rate and their corresponding preambles. For example, an access terminal that has reported DRC 5 may operate such that it should only receive preambles corresponding to (2048, 4, 128) among the multi-user packet formats mapped to it. Access nodes and access terminals may determine one of two operations using messages or configuration attributes.

table 5

TrafficMACIndex 8 MUP Preambles Included 1 Use Biggest MUP 0 or 1 MUPPreamble1 0 or 7 MUPPreamble2 0 or 7 MUP Preamble3 0 or 7 MUPPreamble4 0 or 7 MUP Preamble5 0 or 7

Table 5 shows an exemplary message structure indicating a relationship between forward rate information and a detected preamble proposed in an exemplary embodiment of the present invention. In Table 5, the added UseBiggestMUP field is a field used to instruct the access terminal to detect only the largest multi-user packet format and its associated preamble compatible with the corresponding rate information when reporting the rate information. Thus, when this field has a value of '1', the access terminal only attempts to detect the largest multi-user packet format and its associated preamble that is compatible with its reported forward rate information, whereas if this field has a value of '0' , the access terminal attempts to detect all multi-user packet formats compatible with the forward rate information and their associated preambles.

Table 6

Table 6 shows exemplary configuration properties indicating a relationship between forward rate information and detected preambles proposed in an exemplary embodiment of the present invention. In Table 6, the added configuration attribute UseBiggestMUP is used to instruct the access terminal to detect only the largest multi-user packet format and its associated preamble compatible with the corresponding rate information when the access terminal reports the rate information . Thus, when this configuration attribute has a value of '0x01', the access terminal only attempts to detect the largest multi-user packet format and its associated preamble compatible with its reported forward rate information, whereas if this configuration attribute has a value of ' 0x00', the access terminal attempts to detect all multi-user packet formats compatible with the forward rate information and their associated preambles.

Unlike the exemplary messages of Tables 5 and 6, additional optional messages may be configured such that the access terminal and the access node detect a multi-user packet format in multiple multi-user packet formats compatible with the forward rate information reported by the access terminal. Certain ones, and multiple preambles corresponding thereto.

In an exemplary embodiment of the invention, an access node allocates preamble groups to access terminals in the following manner.

If the number of access terminal identifiers in use in the sector is less than or equal to 128, the access node assigns unused access terminal identifiers numbered 128 or lower to new multicarrier users and uses The single-user group corresponding to the symbol, and the multi-user group using the pre-defined preamble No. 66 to No. 70 perform data communication.

If access terminal identifiers higher than number 128 are required due to an increase in the number of access terminals, the access node assigns identifiers lower than number 128 to certain legacy multicarrier users (e.g., assigned 40 multi-carrier users with identifiers No. 45) allocating new preamble groups proposed in exemplary embodiments of the present invention (for example, No. 40, No. 41, No. 42, No. 43, No. 44) and higher than No. 128 A new identifier for the id (for example, 145 to 150). In this case, legacy assigned identifiers 45 to 50 can be reused for legacy access terminals that do not support multi-carrier systems.

If there is a new multicarrier access terminal that requires a new identifier, the access node assigns the access terminal an identifier higher than number 128 and one of the above assigned preamble groups numbers 140 to 150.

If the number of access terminals continues to increase, the access node assigns new multicarrier users to other multicarrier users assigned identifiers below 128 (e.g., multicarrier users assigned identifiers 80 to 90) Preamble groups (eg, No. 80, No. 81, No. 82, No. 83, No. 84) and new identifiers higher than No. 128 (eg, No. 180 to No. 190). The legacy assigned identifiers 85 to 90 can be reused for legacy access terminals that do not support multi-carrier systems.

Operations of an access terminal allocated a new preamble group proposed in an exemplary embodiment of the present invention, and operations of an access node will now be described with reference to the accompanying drawings.

4 is a flowchart illustrating preamble detection operations for an access terminal assigned a preamble set for a multi-user packet, according to an exemplary embodiment of the present invention.

Referring to FIG. 4, an access terminal determines at step 401 whether an identifier assigned to it is less than number 128 when it starts preamble detection. If the assigned identifier is less than number 128, the access terminal at step 403 attempts to detect the preamble corresponding to the assigned identifier. If the access terminal detects a corresponding preamble at step 405, it proceeds to step 413 to perform a packet reception operation, considering that a single user packet has arrived at the access terminal itself.

If it is determined in step 401 that the assigned identifier is greater than or equal to number 128, or if the access terminal fails to detect the corresponding preamble in step 405, then the access terminal determines in step 407 whether it is assigned the identifier of the present invention. A preamble set for a multi-user packet (MUP) proposed in an exemplary embodiment. If the access terminal is not assigned a preamble group, the access terminal proceeds to step 409 to attempt to detect the preambles (preambles 66 to 70) used to transmit legacy fixed multi-user packets. Thereafter, if the access terminal successfully detects the preamble at step 411, the access terminal proceeds to step 413 to perform a packet reception operation in consideration of the multi-user packet arriving at the access terminal itself. However, if the access terminal fails the preamble detection at step 411, the access terminal proceeds to step 419, ending the preamble detection operation.

If it is determined in step 407 that the access terminal has been assigned the preamble group proposed in the exemplary embodiment of the present invention for multi-user grouping, the access terminal attempts to detect the preamble group belonging to the assigned preamble group in step 415. , or the preamble used to send legacy multi-user packets (MUP). If the access terminal's preamble detection at step 417 is successful, the access terminal proceeds to step 413 to perform a packet receive operation, considering that a multi-user packet (MUP) arrived at the access terminal itself. However, if the access terminal fails the preamble detection at step 417, the access terminal proceeds to step 419, ending the preamble detection operation.

FIG. 5 is a flowchart illustrating a data transmission method performed by an access node according to an exemplary embodiment of the present invention. In this operation, the access node schedules and transmits data to access terminals assigned preamble groups for multi-user packets, as well as to other access terminals.

Referring to FIG. 5, an access node determines in step 501 whether it is transmitting or retransmitting specific data in a current time slot 't'. If the access node has a packet currently being sent, the access node proceeds to 523 and sends the corresponding packet. However, if at step 501 the access node has no packets being transmitted, the access node determines at step 503 the access terminal (AT) whose scheduler will reschedule the sending data and also determines the data rate for that access terminal . Thereafter, the access node determines at step 505 whether the identifier of the corresponding access terminal is less than number 128. If the identifier of the corresponding access terminal is less than number 128, the access node determines at step 509 whether it will send data for the corresponding access terminal using a multi-user packet (MUP). If the access node determines at step 509 to use a single-user packet, then at step 511, the access node generates a single-user packet containing the data of the corresponding access terminal and uses the single-user packet corresponding to the identifier of the corresponding access terminal. The single-user packet is sent with the preamble of the packet. However, if the access node determines to use Multi-User Packet (MUP) at step 509, then at step 513, the access node additionally schedules all access terminals in the sector to additionally transmit using Multi-User Packet (MUP). data. Afterwards, in step 515, the access node generates a multi-user packet (MUP) including corresponding data, and transmits the multi-user packet (MUP) using the preamble used for transmitting a conventional multi-user packet.

If it is determined in step 505 that the identifier of the corresponding access terminal is greater than or equal to number 128, then the access node determines in step 507 whether it has allocated the corresponding access terminal for multiple Preamble group for User Packet (MUP). If the access node has not allocated a preamble group, the access node proceeds to step 513, scheduling data to be additionally transmitted using multi-user packets (MUPs) for all access terminals in the sector. Afterwards, in step 515, the access node generates a multi-user packet (MUP) including corresponding data, and transmits the multi-user packet (MUP) using the preamble used for transmitting a conventional multi-user packet (MUP).

If it is determined in step 507 that the access node has assigned a preamble group to the corresponding access terminal, then the access node determines in step 517 whether it will use one of the preamble groups proposed in the exemplary embodiment of the present invention. The preamble sends a multi-user packet (MUP). If the access node determines to use a preamble in the preamble group proposed in the exemplary embodiment of the present invention in step 517, then in step 519 the access node schedules an access terminal assigned the same preamble group Data to be additionally transmitted using a multi-user packet (MUP). Afterwards, in step 521, the access node generates a multi-user packet (MUP) including corresponding data, and transmits the multi-user packet (MUP) using a preamble belonging to a preamble group.

If the access node determines not to use the preamble group proposed in the exemplary embodiment of the present invention in step 517, then the access terminal proceeds to step 513 to schedule all access terminals in the sector to use the multi-user grouping ( MUP) additionally sent data. Afterwards, at step 515, the access node generates a multi-user packet containing the corresponding data, and transmits the multi-user packet using the preamble used to transmit a conventional multi-user packet.

6 is a block diagram of an access node 610 and an access terminal 620, according to an exemplary embodiment of the invention.

Referring to FIG. 6 , an access node 610 receiving DRC information includes a scheduler and controller 611 , a Radio Frequency (RF) unit 613 , and a data queue 615 . An access terminal 620 that transmits DRC information includes a transceiver (or front end unit) 621 , a demodulator 623 , a decoder 625 , a controller 627 , an encoder 629 , and a modulator 631 .

The data queue 615 of the access node 610 stores the data received from the upper node in the queue for each individual access terminal or service. The scheduler and controller 611 selectively controls stored data for specific users or specific queues by taking into account DRC information (ie, forward channel conditions) sent by access terminals, traffic attributes, and fairness. Among them, the scheduler performs the scheduling operation according to the exemplary embodiment of the present invention, and the controller controls the operation of transmitting data using the preamble group according to the exemplary embodiment of the present invention allocated for each individual access terminal. RF unit 613 transmits selectively controlled data signals to access terminal 620 .

In access terminal 620 , demodulator 623 demodulates signals received via transceiver 621 , and decoder 625 decodes the demodulated signals and provides the decoded signals to controller 627 . If the signal from the access node 610 is configured in a preamble group according to an exemplary embodiment of the present invention, the access terminal 620 performs the operations shown in FIG. 5 . If there is data to send, access terminal 620 encodes the corresponding data with encoder 629 , modulates the encoded data with modulator 631 , and transmits the modulated data to access node 610 via transceiver 621 .

To assist the access node 610 in performing scheduling, the access terminal 620 measures the strength of the pilot channel transmitted from the access node 610, determines the DRC (i.e., the data rate at which data can be received from the corresponding access node 610), and communicates via The transceiver 621 sends the determined DRC to the access node 610 .

As can be seen from the foregoing description, the exemplary embodiments of the present invention can transmit data to an increased number of users without affecting existing access terminals when the multi-carrier transmission system additionally uses access terminal identifiers.

While this invention has been particularly shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the principles set forth in the appended claims and Their equivalents define the spirit and scope of the invention.

Claims (13)

1. A method for sending data by an access node to an access terminal in a CDMA system, the method comprising: determining a set of preambles for a multi-user packet MUP to an access terminal; providing, by an access node, the set of preambles for the MUP to the access terminal; checking data rate control DRC information received from the access terminal and determining a packet format for the MUP by using the checked DRC information; and The MUP is sent to the access terminal using a preamble set corresponding to the access terminal. 2. The method of claim 1, wherein the access node provides the set of preambles for a MUP to the access terminal during session configuration. 3. The method of claim 1, wherein the access node assigns the access terminal a Medium Access Control Identifier (MAC ID) having a number of 128 or above. 4. The method of claim 1, wherein Each preamble of the set of preambles is determined based on the information about the preambles and the size of the MUP to the access terminal. 5. an access node of a code division multiple access CDMA system, the access node comprising: a controller for determining a preamble group for a multi-user packet MUP to an access terminal, examining data rate control DRC information received from the access terminal, and determining a packet for the MUP by using the examined DRC information Format; A radio frequency unit, configured to send a preamble set to the access terminal, and send the MUP using the preamble set to the access terminal. 6. The access node of claim 5, wherein the controller assigns a medium access control identifier (MAC ID) having a number of 128 or more to the access terminal. 7. The access node of claim 5, wherein the controller determines each preamble of a preamble group based on information about preambles and a size of a MUP to the access terminal. 8. A method for receiving data by an access terminal in a Code Division Multiple Access (CDMA) system, the method comprising: Send data rate control DRC information to the access node; receiving a preamble set for receiving a multi-user packet MUP from an access node; detecting at least one preamble using the received set of preambles; and It is determined whether at least one preamble is assigned to the access terminal, a MUP having a packet format determined by using the DRC information is received from the access node, and the received MUP is demodulated and decoded. 9. The method of claim 8, wherein each preamble of a preamble group is determined based on information about preambles and a size of a MUP to the access terminal. 10. The method of claim 8, wherein the access terminal receives the set of preambles for a MUP during session configuration with the access node. 11. An access terminal of a code division multiple access CDMA system, the access terminal comprising: a radio frequency RF unit for sending data rate control DRC information to an access node, receiving from said access node a preamble group for receiving a multi-user packet MUP, and receiving from the access node a MUP in packet format; a controller for controlling the DRC to be sent to the access node, detecting at least one preamble using the received set of preambles, and determining whether the at least one preamble is assigned to the access terminal; and A decoder for decoding the received MUP. 12. The access terminal of claim 11, wherein each preamble of a preamble group is determined based on information about preambles and a size of a MUP to the access terminal. 13. The access terminal of claim 11, wherein the controller receives the set of preambles for a MUP during session configuration with the access node.